This invention relates to the field of fishing and more specifically to an improvement in the fishing line used in long line fishing.
Long line fishing is a profession that employs miles of rope, cable or monofilament line deployed along the depths of an ocean for demersal species or supported horizontally in the water column from floats with hundreds or, even thousands, of hooks for palegic species.
Originally these long lines were made from rope set and hauled, by hand, from small boats. Pincher type power driven haulers made larger systems feasible for larger vessels wherein the rope was usually stored in large tubs. Later, some mid-size boat fleets found it preferable to haul and store rope lines on large hydraulic driven reels eliminating the need for a pincher hauler and the storage tubs.
In the 1970""s, some fishermen started using large monofilament for the main lines instead of ropes. They found that it fished better. Monofilament long lining systems expanded steadily for the mid-sized fleets of boats 12 to 30 meters in length.
In the late 1990""s, monofilament long line gear was beginning to penetrate more demanding markets of larger boats. These boats, up to 60 meters, have large crews and can set and haul up to 70 or 80 miles per day.
Some activists and environmental groups have expressed concerns about long line fishing because of the accidental harvesting of protected or endangered species of fish and mammals. Also, birds, such as the endangered Pacific albatross and others, are attracted to the bait deployed along the line. As conventional line is unreeled behind the boats with baited hooks, the line and the bait tend to remain on or near the surface for a period of time before submerging. Unfortunately in trying to eat the bait, some of the birds become fatally entangled with the line or hooks.
The fishing industry has responded to these concerns by using different techniques and equipment to lessen the environmental impact of long line fishing. Line setting devices deploy the line slack so that it can sink faster or use a underwater chute to deploy the baited hooks several meters below the surface before they are exposed. These techniques require additional expense and effort on the part of the fisherman and vessel.
The properties of highly molecularly oriented Nylon lines in current usage, such as Nylon 6-6/6 copolymer monofilament 3.6 mm line test at over 1200 lb. tensile strength and has a specific gravity of about 1.12 to 1.13. The line sinks slowly in salt water which has a specific gravity of about 1.027. Thus, the line and bait may lay on the surface of the water for a period of time wherein the birds can feast on the bait with the resulting consequences.
What is needed in the art is a fishing line with conventional properties of strength, elongation creep, wear and flexibility that will submerge quickly to reduce the time bait remains on or near the surface of the water. Heavy monofilament could replace or compliment current methods to reduce bird catch.
U.S. Pat. No. 5,131,218 to Berger discloses a fishing rope with floating and sinking portions. The rope is made up of filaments formed into a portion that has a specific gravity less than 1 and a portion of the rope has a specific gravity greater than 1.
The Burgess patent, U.S. Pat. No. 4,952,344, discloses a fly fishing line with a nylon or Kevlar core pulled through an extruder and coated with other polymers, such as polyurethane. The coating may have a filler to increase density. The fillers may be pulverized lead, barium sulfate, or tungsten and may be added to result in a specific gravity of 2 or more. The density of the line may be changed along its length from a floating line to a sinking line.
Matsumoto et al, U.S. Pat. No. 3,808,725, discloses a fishing net with a high specific gravity made with hollow monofilaments with a core of spaced apart fiber segments of metal or metal alloys. A specific gravity of 2.9 was obtained in one example. The monofilaments were produced by simultaneously extruding a core and a polymeric covering.
This invention is a composite heavy fishing line for reducing environmental damage defined as an indefinite running length of flexible polymeric monofilament material containing a mixture of particulate metals and/or salts thereof, such as copper, brass or tungsten as a heavy metal and silicon carbide or barium sulfate as a salt. There are several other metals with acceptable properties of weight and price. Some of the most suitable are too expensive like gold, Platinum and silver. Others are unsuitable because of environmental reasons for example mercury, uranium, and potentially lead. Any heavy affordable powdered material could be used. Materials with a specific gravity of as low as 2.0 could be used in higher quantities, however, monofilament properties will suffer compared to lower amounts of a higher specific gravity material like tungsten with a specific gravity of 19. The selection and amount of material depends on the sink rate required, the physical properties and the cost limitaions.
The mixture is added to the core of the line wherein the improved fishing line has a specific gravity over 1.15 and rapidly sinks in water to prevent birds from becoming entangled with said fishing line.
Such a line fishes better than conventional lines. The demersal fishermen prefer such a heavy line that sinks faster and moves less on the bottom. The palegic fishermen prefer a heavy line that descends steeply between floats and is less disturbed by underwater currents.
The line may be used in making nets wherein the properties of the net repeat those of currently weighted nets. However, nets made in accordance with the instant invention will sink when untended thereby lessening the environmental impact caused by lost nets. For instance, an edge of a conventional trawler net floats on the water surface while the majority of the net is submerged. If the net is lost, due to rigging failure, high seas, or the like, the net will continue to float where it can snare marine life. Further, such a net may eventually wash on shore where it can drag across and foul coral reefs. The use of the instant invention would eliminate the need for heavy weights for a lower edge and buoyancy keepers. Thus, the overall weight of the net is reduced wherein a negative buoyancy can be obtained without exceeding vessel rigging capacities.
Also disclosed is a methods of making composite heavy fishing lines for rapid submersion comprising the steps of
1) preparing an extrusion compound of polymeric material;
2) passing said material to an extruder;
3) metering said particles to said extruder; and
4) extruding an indefinite length composite line with a specific gravity of at least 1.15.
Copper powder with a specific gravity of 8.8 was added to a nylon 6/6xe2x80x946 copolymer fish line of 2.0 mm with the following results.
It is clear that by simply adding heavy material in the polymer while forming the line the sink rate can be increased, but with significant loss in physical properties. Improvements can be made by using higher specific gravity materials such as tungsten instead of copper, but with a increase in cost. This method may be useful for some applications, but the most demanding applications must be accomplished without the significant losses in strength.
Accordingly, it is an objective of the instant invention to teach a method of making a composite fishing line by co-extrusion of a core of heavier particles and a polymeric cover capable of use in long line fishing that will submerge quickly upon contact with the water.
It is another objective of the instant invention to teach a method of combining the heavier particles as an aggregate slurry for continuous co-extrusion with a polymeric material.
It is a further objective of the instant invention to teach a composite fishing line of indefinite length composed of a continuous polymer with a core of metal particles having a specific gravity of about 1.4. without significant losses in physical properties.
It is yet another objective of the instant invention to teach an indefinite length fishing line of polymeric material with about 10% by volume of metal particles.
Still another objective of the instant invention to teach the use of a fishing line having sinking properties that cannot be disabled by an operator.
It is yet another objective of the instant invention to teach the use of a fishing line that allows authored to instantly recognize whether a fishing boat is conforming to the fishing line sinking requirements, wherein the fishing line cannot be hidden and is of such size that substitution is not possible.